When a migraine headache occurs, pulsating or throbbing pain is usually felt on one side of the head, but it may occur on both sides. Physical activity, bright light, loud noises, and certain odors may make the headache worse. The pain is frequently accompanied by nausea, vomiting, and sensitivity to sounds, light, and/or odors.

Migraines are 3 times more common among women. In the United States, about 18% of women and 6% of men have a migraine at some time each year.

Migraines may become chronic. That is, they occur 15 or more days a month. Chronic migraines often develop in people who overuse drugs to treat migraines.

Did You Know...

More than half the people who have migraines have close relatives who also have them.

After age 50, headaches usually become significantly less severe or resolve entirely.

Migraines occur in people whose nervous system is more sensitive than that of other people. In these people, nerve cells in the brain are easily stimulated, producing electrical activity. As electrical activity spreads over the brain, various functions, such as vision, sensation, balance, muscle coordination, and speech, are temporarily disturbed. These disturbances cause the symptoms that occur before the headache (called the aura). About 25% of people experience an aura.

The headache occurs when the 5th cranial (trigeminal) nerve is stimulated. This nerve sends impulses (including pain impulses) from the eyes, scalp, forehead, upper eyelids, mouth, and jaw to the brain. When stimulated, the nerve may release substances that cause painful inflammation in the blood vessels of the brain and tissues covering the brain. The inflammation accounts for the throbbing headache, nausea, vomiting, and sensitivity to light and sound.

Possible Triggers for Migraines

Estrogen (the main female hormone), when levels increase or fluctuate

Birth control pills, which contain estrogen

Lack of sleep, including insomnia

Changes in the weather, particularly barometric pressure

Red wine

Certain foods

Hunger (as when meals are skipped)

Excessive stimulation of the senses (for example, by flashing lights or strong odors)

Keep a headache diary: Write down the number and timing of attacks, possible triggers, and response to treatment. With this information, triggers may be identified and eliminated or avoided when possible.

Was This Page Helpful?

Also of Interest

Test your
knowledge

Pilonidal disease is an infection caused by a hair that injures the skin at the top of the cleft between the buttocks. For unknown reasons, sometimes a hair irritates and grows into the skin, forming a cavity that may contain hair. This cavity typically forms at the top of the cleft between the buttocks. What is this cavity called?

Merck and the Merck Manuals

Merck & Co., Inc., Kenilworth, NJ, USA is a global healthcare leader working to help the world be well. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world. The Merck Manual was first published in 1899 as a service to the community. The legacy of this great resource continues as the Merck Manual in the US and Canada and the MSD Manual outside of North America. Learn more about our commitment to Global Medical Knowledge.